The Echinoid Directory

Contributed by Andreas Kroh, August 2010

Hypsiechinus Mortensen, 1903, p. 81.

Diagnostic Features	Test small; profile low domal. Apical disc large, dicyclic. Forming a raised knob in females (brood-protecting, the juveniles carried around the elevated apical disc in females). Ambulacral plating trigeminate, compound in echinid style. Pore-pairs small, arranged uniserially, forming slight arcs only close to the peristome. One primary tubercle to each compound plate close to the pore zone, plus one smaller perradial tubercle. Interambulacral plates with central primary tubercle and few smaller secondary tubercles. No obvious sculpturing or sutural pits, except in females, where the uppermost interambulacral plates bear a radiating sculpture around the secondary tubercles. Primary tubercles imperforate and distinctly crenulate. Peristome large without obvious buccal notches. Perignatic girdle with small, unfused auricles. Spines thorny, without cortex, about half of test diameter in length. Globiferous pedicellariae with open blade and 2-3 lateral teeth to each side and single venom glands.
Distribution	Recent; North Atlantic (around Iceland).
Name gender	masculine
Type	Hypsiechinus coronatus Mortensen, 1903, by monotypy.
Species Included	Only the type.
Classification and/or Status	Camarodonta; Temnopleuroida;Trigonocidaridae.
Remarks	Differs from Trigonocidaris by its thorny spines, largely unsculptured corona and its distinct sexual dimorphism. Note that Mortensen placed this genus in the Trigonocidaridae. Mortensen, T. 1903. The Danish Ingolf-Expedition 1895-1896. Vol. 4, No. 2. Echinoidea, pt. 1, 198 pp., 21 pls. Bianco Luno, Copenhagen. Mortensen, T. 1943. A Monograph of the Echinoidea. III, 2. Camarodonta. I. Orthopsidae, Glyphocyphidae, Temnopleuridae and Toxopneustidae. C. A. Reitzel, Copenhagen, vii+553 pp.